Recycling poly-(methyl methacrylate) by pyrolysis in a conical spouted bed reactor

Abstract

The pyrolysis of poly-(methyl methacrylate) (PMMA) has been studied in a pyrolysis plant provided with a conical spouted bed reactor. This reactor is an interesting technology for the pyrolysis of waste plastics due to its excellent hydrodynamic behaviour and its high heat transfer and versatility. A previous kinetic study was carried out in thermobalance, in which the degradation of this polymer was observed to begin at low temperatures, 553 K. Consequently, the activation energy is low compared to other plastics. The influence of temperature on pyrolysis product distribution in the conical spouted bed reactor has been studied in the 673–823 K range. The products obtained at low temperatures are mainly the monomers of the polymer used for the study methyl methacrylate (MMA) and ethyl acrylate (EA). When the pyrolysis temperature is increased, the yield of monomers is lower due to the higher severity of secondary reactions, and there is a significant increase in the yield of gases. The maximum monomer recovery has been obtained at 673 K, with the yields of MMA and EA being 86.5% and 6.2%, respectively.